//Modified from sample code: http://www.hackingwithphp.com/12/3/3/searching-and-filtering-with-xpath

XML_Data_Filter.php

<?php
$time_start = microtime(true); //record the execution time

$xml = simplexml_load_file('data.xml');
$country = '';
$city = '';
$search = '';

if (isset($_GET["search"])) {
  $search = trim(htmlspecialchars($_GET["search"]));
}

if (isset($_GET["country"])) {
  $country = trim(htmlspecialchars($_GET["country"]));
  $country = '[Country="' . $country . '"]';
}

if (isset($_GET["city"])) {
  $city = trim(htmlspecialchars($_GET["city"]));
  $city = '[City="' . $city . '"]';
}

$hotels = $xml->xpath('/Root/Hotel/HotelInfo' . $country . $city);

foreach($hotels as $hotel) {
    if ($search !== '') {
      $hotel_str = strip_tags($hotel->asXML());
      if (strpos($hotel_str, $search) !== false) {
          var_dump(json_encode($hotel));
      }          
    } else {
      echo "Hotel: {$hotel->CompanyName}<br />";
    }
}

echo '<br />Total execution time in seconds: ' . (microtime(true) - $time_start);